JPH04351859A - Electrolyte holder and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a manufacturing method and a manufacturing device for a solid electrolyte holder for an electrode for a chemical battery. CONSTITUTION: A layer of fine grain material containing solid electrolyte or its precursor is formed round a mandrel 28 having a thread on the outside. In order to form unworked holder having an internal thread formed by the threads 34, 38 of the mandrel 28, a layer 46 of fine grain material is uniformly formed by pressurization. The mandrel 28 is turned in the axial direction to be removed from the unworked holder. The unworked holder is sintered to provide a holder shaped like a single polycrystalline ceramic solid electrolyte workpiece.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte holder for electrodes for chemical batteries. In particular, the present invention relates to a method for manufacturing such a solid electrolyte holder, an apparatus for manufacturing such a holder, and a solid electrolyte holder manufactured according to the method.

[0002] According to one aspect of the present invention, a method of manufacturing a solid electrolyte holder for an electrode for a chemical battery is provided, the method comprising a solid electrolyte or its precursor around an externally threaded mandrel. Forming a layer of particulate material, uniformly pressing the layer of particulate material to form a green retainer with internal threads formed by the threads of the mandrel; The steps include axially punching the green cage and sintering the green cage to provide the cage in the form of a single polycrystalline ceramic solid electrolyte fabrication. .

Although the particulate material can in principle be in the form of a slurry, it is preferably in the form of a powder, especially a free-flowing powder.

Uniform compaction will typically be by means of hydrostatic pressure imparted to the powder by a resiliently flexible membrane, such as a latex or polyurethane sheath, in which the mandrel is housed. Pressure molding is usually 10×103
~30×103 psi, preferably 12-18×
103 psi, e.g. 34×103 psi (1
psi = 6.894757 kpa). Essentially, the method can take one of two main approaches, the first of which is to squeeze the coating against the powder layer in the direction towards the inside of the mandrel;
and the second should squeeze the coating against the powder layer outwardly away from the mandrel. In each case a suitable mold, e.g. a split mold, can be adopted around the mandrel, which mold is internally threaded and the threads of the mandrel and the threads of the mold are similar to each other. registered to define an annular space between which the powder is to be squeezed into a layer of desired thickness and shape;
The mandrels are shaped so that they can be placed generally concentrically.

According to the first approach, the particulate material may be a powder, and the powder layer is compressed uniformly against the mandrel by means of the mandrel and a flexible covering that encapsulates the powder layer. Thus, the coating is encapsulated within the mold, the coating is elastically flexible and forms a lining to the mold prior to pressing, and the powder forms a layer of powder. In order to To form the lining, the coating is removed after pressing so that it can spring back resiliently away from the green cage, after which the mandrel and green cage are respectively It is unscrewed from the cage and removed from the mold.

[0006] According to the first approach in more detail, the sheathing can be shaped to provide contact and formation of the lining to the mold, and the sheathing and shape of the mandrel close the bottom of the annular space. arranged vertically, the powder is charged from the top down into the annular space between the coating and the mandrel, with vibrations to consolidate and compact it, so that the upper part of the annular space When the space is filled with powder, it is closed and the coating is uniformly pressed inwardly against the layer and mandrel by water passing through pinholes suitably present in the mold under pressure. After pressurization, the coating can spring back resiliently away from the pressurized green cage to line the mold. If desired,
The mandrel can first be unrolled from the green cage and then the green cage is removed from the mold, or vice versa. Removal of the raw retainer from the mold may be accomplished by unrolling the raw retainer from the mold or, if the mold is a split mold, by splitting the mold. Dew. To facilitate punching, the mandrel can be tapered on either or both of the molds from the wide end to the narrow end, and the punching is done from the narrow end to the wide end. done in the direction.

Of course, instead of using a relatively thin coating within the mold, the mold and coating can be combined into a single unit made of latex or polyurethane, which unit is made of a thin, self-supporting material. It can be considered as a covering or as a thick elastically flexible self-supporting type. This can be placed around the mandrel, filled with powder and pressurized, and then moved away from the green cage to facilitate unrolling of the green cage. It rebounds elastically.

According to the second approach, the particulate material may also be a powder, and the powder layer encapsulates the mandrel and includes a flexible material disposed between the mandrel and the powder layer. The powder layer is uniformly pressed outwardly away from the mandrel against the mold enclosing the powder layer. In this way, the coating is elastically flexible and forms a lining to the mandrel prior to compaction, and the powder is placed in the space between the coating and the mold to form a layer of powder. the pressure forming is due to liquid introduced into the coating between the coating and the mandrel;
Fluid pressure is then removed after pressurization to allow the coating to spring back resiliently away from the green retainer to form a lining to the mandrel and the green retainer. The cages are each unscrewed from the cage and removed from the mold.

[0009] In more detail, according to the second approach, the sheath is shaped to form and contact the lining on the mandrel, and the metal sheath and mold again close the bottom of the annular space and similarly arranged vertically, the powder is likewise charged into the annular space from above, but in this case between the sheathing and the mold, and the pressurization of the sheath is carried out after closing the upper part of the annular space by the mandrel. Externally to the coating and to the mold via pinholes suitably present within. After pressurization, the coating is able to spring back resiliently away from the pressurized green retainer to line the mandrel. The green cage is then removed from the mold and
The mandrel was then rolled out of the green cage as described above for the first detailed approach.

Naturally, a hybrid approach can be adopted, whereby two coatings are used, lining the mandrel and mold respectively, the powder is charged between the coatings, and the pressure is done inwardly and outwardly at the same time. This hybrid approach is such that after the two coatings have resiliently rebounded to line the mandrel and mold, respectively, by removal of hydrostatic pressure, the mandrel and the raw artifact are removed, especially if If the mandrel and mold are tapered, each has the advantage of being easily rolled out.

[0011] Thus, according to the hybridization approach, the particulate material may again be a powder, the mandrel and the powder layer being encapsulated by a flexible outer covering placed in the mold, and , a flexible inner coating is provided between the mandrel and the powder layer, the powder layer being simultaneously squeezed inwardly by the outer coating by a fluid introduced into the mold outside the coating. , and is squeezed outwardly away from the mandrel by the inner sheath by fluid introduced into the inner sheath between the inner sheath and the mandrel. Each coating is elastically flexible, and the inner and outer coatings line the mandrel and mold, respectively, prior to pressing, and the powder is applied to the space between each coating to form a powder layer. and fluid pressure within the inner sheath and between the mold and the outer sheath, respectively, allows the inner and outer sheaths to rebound, respectively, to line the mandrel and the mold. removed after pressure molding,
The mandrel and green cage are then each unscrewed from the cage and removed from the mold.

When the mold is employed, it is internally threaded and removal of the retainer from the mold is accomplished by unscrewing the retainer axially from the mold.

Naturally, the threads of the mandrel and mold can be provided by a single helical thread, or they can be of multiple pitches employing two or more helical threads. obtain.

[0014] The particle size of the powder employed may be such that at least 80 volume percent thereof has a particle size of less than 55 μm in size, preferably a proportion thereof less than 30 μm.

Regarding the precursor of the solid electrolyte, a powder mixture is envisaged which, when sintered, is converted into a solid electrolyte and at the same time forms a polycrystalline artifact. A number of such precursor powder mixtures are well known in the art of chemical cell solid electrolyte separators, and it is understood that either suitable powders containing such precursors or the solid electrolyte itself may be employed. It should be emphasized that the tying process is also conventional and is a novel feature of the present invention with respect to the practical formation of a green cage.

After removal of the mandrel from the green cage and removal of the green cage from the mold, the green cage is heated in a conventional manner to a suitable sintering temperature, eg, US Pat. No. 4,732,
As described in No. 741, Example 1550-
It may be sintered by heating at 1700°C, typically 1600-1630°C. This means that the surface of the retainer is very close to whatever is used to support the raw retainer, whether it is erected on one end or hung vertically or lying on its sides, in any case. It can be accomplished without contact.

[0017] Typically, the mandrel has a base or guide shaft at one end thereof, eg, at its broad end if it is tapered. The method may therefore include embedding the opposite or narrow end in the powder such that the holder has an opening at one end thereof and is closed at the other end. In this case, a suitable ceramic powder is annularly shaped to form a collar at the open end of the tube, the remainder of which can be sintered entirely to provide an ionically and electrically insulating collar at the open end of the tube. It can be loaded into the space.

In practice, the solid electrolyte is usually β-alumina or β″-alumina, thus a powder containing β-alumina or β″-alumina, or a powder as described in US Pat. No. 4,732,741. The alumina-containing powder may be a precursor powder that is converted to the alumina-containing powder by heating to a sintering temperature such as In this case, the insulating tsuba is α
- Can be alumina, α-alumina powder or a precursor of α-alumina powder used to form the collar of the green cage. Of course, other types of solid electrolyte retainers can be made in a similar manner.

[0019] Suitable binders may be employed to bind the powder and strengthen the green cage in a conventional manner. For this purpose, the applicant has used polyethylene glycol wax, such as polyethylene glycol wax, with a
Waxes with a molecular weight of 0.00 and which volatilize during sintering without destroying the green artifact have been found to be suitable.

For the second approach described above, it may be helpful to apply a suitable vacuum between the mandrel and the coating in order to tightly adhere the coating to the mandrel before pressing occurs. This vacuum can then be reapplied after pressing to help the coating spring back resiliently away from the green retainer to line the mandrel. For the first approach above, after pressurization, a vacuum is applied to the coating as well to help it rebound elastically away from the green cage and to line the mold. Can be applied between molds. It should also be noted that while the present invention has particular utility in the production of electrolyte holders for high temperature batteries, it could in principle also be used in the production of similar holders for room temperature batteries. .

According to another aspect of the invention, there is provided an apparatus for use in the above method.

The device includes an externally threaded mandrel and a flexible sheath, the mandrel defining an annular space for containing particulate matter to be uniformly squeezed by the sheath. It can be housed within the sheath for placement around the mandrel.

The device is thus for the production of solid electrolyte holders for electrodes in chemical cells, and as mentioned above, the coating can be shaped or supported to be threaded; The mandrel may be arranged in the coating to provide an annular space, threaded around the mandrel, for accommodating the powder to be uniformly compressed by the coating, and The space is bound at one end by the covering.

[0024] The device has the coating between the mandrel and the mold, and the space defined inside the mold, so that the mandrel is housed between the mold and the mandrel. A obtaining mold may be included, the mold and the mandrel radially defining the interior and exterior walls of the space, respectively. The mold can then be internally threaded.

[0025] The covering may be elastically flexible and forms a lining to one of the walls of the space. Alternatively, there may be two coverings, each forming a lining to the interior and exterior walls of the space.

[0026] The mandrel and the mold may be correspondingly threaded, the mandrel having the coating between the mold and the mandrel, and the covering of the mold and the mandrel. It may be housed within a mold having the space defined therein. Thus, the sheathing can be lined to the mandrel, supported by and threaded, and the space defined between the sheathing and the mold. or alternatively, the coating can be a lining to the mold;
Supported by a mold and threaded, the space is defined between the sheath and the mandrel.

As mentioned above, there can be two coatings, one forming the lining to the mold and the other forming the lining to the mandrel, so that the space is Defined between two coatings. Both sheathings may be simple cylindrical tubes in the shape of the mold or mandrel they line, or they may be shaped to be self-supporting, retaining their shape, and be threaded. . Therefore, in simple cases, all that is needed is a mandrel placed on a shaped self-supporting threaded sheath, with accompanying inward pressing of said sheath. Powder can be charged between the coatings. Alternatively, such a coating may be placed in a mold with the powder being charged between the coating and the mold with outward pressing of the coating. however,
As mentioned above, it is expected that the mandrel and mold will normally be used together.

[0028] The mold may be a split mold. The mold can have an axially tapered interior, and the mandrel can also be axially tapered.

In a particular embodiment of the device, it has a hollow cylindrical outer housing that can be split lengthwise and is provided with several axially spaced outer annular clamps; and a mold having an exterior surface and supported in the housing by the clamp. In this case, the mandrel may have a cylindrical base that plugs one end of the housing and a cylindrical plug that is used to plug the other end of the housing. The type is, for example,
It can be split lengthwise into two or three parts, and the mold, the mandrel and the plug each have one or more suitable channels for transmitting hydrostatic pressure to the coating for uniform pressing. Or it can have a pinhole.

The invention also extends to a solid electrolyte holder for holding the electrodes of a chemical cell whenever manufactured by the method described herein.

Typically, the retainer will have relatively closely spaced threads or fins when it is intended to hold a molten alkali metal cathode, such as a sodium cathode, within it. Probably. And when it is intended to hold an anode, it will have relatively widely spaced fins or threads.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention is illustrated by means of examples in conjunction with the accompanying schematic drawings.

In FIG. 1, reference numeral 10 generally indicates an apparatus according to the invention for use in the method of the invention. The device 10 is in the form of a pressure jig comprising a hollow cylindrical mild steel outer housing that is lengthwise sectioned and held together in position by an outer steel annular clamp 14. The jig 10 is shown in a vertically operable state with its upper end closed by a cylindrical resiliently flexible latex plug 16. Instead of latex, flexible polyurethane can be used as plug 16.

Concentrically disposed below the plug 16 within the housing 12 is a longitudinal split 20 whose portions are co-supported by the housing 12. The upper part of the mold 20 has a plug 24 of similar material to that of the plug 16.
It has a central opening 22 which is closed. The mold 20, described in more detail below, has a threaded hollow interior through which an aperture 22 passes;
has an opening 26 at its lower end leading into the interior thereof.

A threaded mandrel 28 is shown concentrically disposed within the hollow interior of the mold 20 in loose threaded engagement with the mold. The mandrel 28 has a bottom 30 received in the mouth 26 and a central shaft or mandrel 32 provided with a helically extending thread 34 extending from the bottom 30 to the other end of the mandrel 32. The mandrel 32 has a large number of pinholes (not shown).
has a central passageway 36 communicating radially outwardly therefrom to the surface of mandrel 28.

As shown in FIG. 1 and described above, the internal cavity of the mold 20 has internal helically extending threads 38.
It has a threaded shape.

The pitch of the threads 34 is the same as that of the threads 38, and the mandrel 28 may be positioned within the mold so that it is spaced radially inwardly from the wall of the cavity of the mold 20. and the thread 34 vane (flight
) is axially spaced from the vanes of thread 38;
Mold and made to size. The mold 20 and the mandrel 28 thus define a screw-shaped annular space 40 between them. Within this space 40 is provided adjacent the surface of the mandrel 28 a resiliently flexible, hermetically continuous latex coating 42 that fits snugly around the mandrel 28 as a lining. The helical shaped space 40 therefore allows the coating 42 and the mold 20
exists between the inner surfaces of

In use, the jig 10 is assembled as shown in FIG. 1, with the clamp 14 holding the housing 12 against the external cylindrical surface of the mold 20 and against the plug 16 and the mandrel. It can be seen that it is held snugly against the bottom of 28. The plug 16 thus seals one end of the housing 12 and the bottom 30 of the mandrel 28 has an open end 44 of a sheath 42 sandwiched between the housing 12 and the mandrel 28.
Seal the lower end of the housing.

To manufacture an electrode holder in accordance with the present invention, jig 10 is assembled as shown in FIG. 1, except that two plugs 16, 24 are removed, and mandrel 28 is assembled. The lowermost clamp 14 around the bottom 30 is sufficiently tightened only to prevent powder from escaping from the space 40 below.

A suitable powder, such as β- or β″-alumina, of a particle size such that 80% by volume of the sand has a size less than 55 μm is passed through the openings 22 in order to solidify and consolidate the powder. With appropriate vibration, the powder is charged into the space 40 between the coating 42 and the mold 20. When the space 40 is filled with powder,
Plug 24 is inserted into position and final tightening of clamp 14 is followed to tightly seal housing 12 against plug 16 and the bottom 30 of mandrel 28.

[0041] The water then enters the passageway 34 inside the sheathing 42.
and the space 4 through various pinholes in the mandrel.
From the powder bed, indicated at 46, which is filled to zero, a suitable pressure is introduced to uniformly pressurize the raw screw-shaped hollow electrode holder. This pressure is, for example, 24×103 ps
It can be i.

The pinhole is inserted into the mandrel 2 under the pressure.
8 and the coating 42 over the surface of the mandrel 32 and the threads 34 of the mandrel 28, which water consolidates the powder against the inner surface of the cavity of the mold 20. Squeeze the coating outward.

After uniform pressing with hydrostatic pressure, the water pressure is removed and the coating 42 is spaced apart from the powder 46 and away from the raw artifact formed from the powder.
contact with the mandrel 28 and bounce back.

At this stage, after releasing the clamps 14, in particular the lowermost clamp 14, the mandrel 28, together with the sheathing 42, is unscrewed axially downwards from the inner surface of the green cage. The green retainer is then removed from the jig 10 by removing the clamp 14 and splitting the housing 12 and mold 20 lengthwise.

The electrode holder is then sintered into a polycrystalline artifact by heating in air to a suitable temperature, eg, according to a heating schedule of the type described in US Pat. No. 4,732,741. Ru. This is conveniently done by standing the holder vertically at its ends to minimize contact between the holder and the crucible surface of the furnace. Alternatively, the green cage is suspended within or placed to the side of the furnace crucible under conditions where the surface of the green cage has little contact with any crucible surface.

The unique feature of this method is that α-
In order to form an alumina ring, an α-alumina powder of similar particle size to that of the β- or β″-alumina is first introduced into the space 40. β- or β″ of the holder to provide a sintered holder mouth that is sintered hermetically and integrally with the vessel but is ionically and electrically insulating. - Will be pressed together with alumina and sintered.

Turning to FIG. 2, the structure is similar to that of FIG. 1, and like reference numbers refer to like parts unless specified otherwise.

The difference between FIG. 2 and FIG. 1 is that the passage 36 and the pinhole in the mandrel 28 are omitted and are replaced by one or more suitable passages (not shown) in the plug 16, for example. The port 20 is provided with one or more suitable similar passageways and a plurality of pinholes (not shown) through which communication can be conducted to the outside.

In the case of FIG. 2, the covering 42, unlike in FIG. Instead, it is open and plug 16 and type 20
The plug 24 projects outwardly through an opening 22 having a periphery of the open upper end of the sheathing which is pressed between the upper parts of the cover and which the plug 24 closes off.

In this case, the space 40 is between the sheathing 42 and the threaded part of the mandrel 28. This space is vibrated filled with powder through the open top end of the sheathing 42, and the space 40 is filled with powder to the extent shown in FIG. 2, with a small open space 48 above the powder, as shown in FIG. When filled, uniform pressing is performed inwardly through the channels and pinholes to squeeze the coating 42 against the powder and the powder against the mandrel 28.

After pressing, the pressure is removed and the coating 42, which is resiliently flexible and shaped to automatically conform to the inner surface of the mold 20, is removed from the green cage and removed from the mold. 2
It bounces off when it comes into contact with 0. The raw retainer and mandrel 28 are then removed together after the clamp 14 is removed.
It can be rolled out from inside the mold 20 in the axially downward direction.

[0052] The mandrel 28 can then be spun from the green cage, which is fired as described above, to sinter it.

If the parts of the pressure-molded middle mold 20 are held firmly together, the outer housing 12
It should be noted in connection with FIG. 2 that in practice may be omitted.

In a hybrid variant of FIGS. 1 and 2, two coatings can be provided lining the mandrel 28 and the inner surface of the mold 20, respectively, and the powder is loaded into the space 40 that would exist between the coatings. entered. In this case, after pressure forming,
Both coatings bounce off the green cage to facilitate both unrolling of the mandrel from the interior of the green retainer and unrolling of the green retainer from the mold.

Although a non-tapered mandrel 28 and mold 20 are shown in FIGS. 1 and 2, it will be appreciated that they are both tapered upwardly, thereby facilitating the punching described above.

Two variations of cages formed by the method of the invention are shown in FIGS. 3 and 4, each designated generally at 50. Both have a central hollow central shaft or mandrel 52 and a single continuous thread 54, the flights of which are also hollow. These retainers 50 have vanes of threads 54 formed by threads 38 of mold 20 (FIGS. 1 and 2);
The vane has a hollow inner surface that communicates with the hollow inner surface of the mandrel 52, formed by the threads 34 of the mandrel 28 (FIGS. 1 and 2). The upper end of the retainer 50 is closed at 56, which at its lower end has a residual β-
or a collar 58 of α-alumina integral with the remainder being β″-alumina. If desired, the lower end of the retainer 50 is provided with the lower end of the retainer with the collar 58. In this respect, a tubular β-alumina extension may be provided, which is indicated by dotted lines 60 in FIGS. It will be appreciated that the coating 42 is squeezed into the space 48 below the plug 24 above the powder surrounding the top of the mandrel 28 to provide a closed upper end for the retainer.

It is an advantage of the invention to provide a simple and easily used method and apparatus for pressing green electrode holders of the type in question. These electrode holders, after sintering, are typically used to contain the electrodes of batteries with a molten sodium cathode, which is placed inside the holder with the anode on its outside, or vice versa. Either.

As shown in FIG. 3, the fins (
When there is a small spacing between the wings or fins of the thread 54, a suitable anode is provided around the exterior of the retainer 50 to surround the thread 54 and to fill the space between the wings or fins of the thread 54. It is expected that a sodium cathode will be provided inside the cage. However, when there is a large spacing between the fins or fins of the thread 54, as shown in FIG. It is expected that the sodium of the cathode is present outside the retainer 50.

[Brief explanation of drawings]

1 shows a schematic side sectional elevational view of a device according to the invention; FIG.

FIG. 2 shows a similar view of another device according to the invention.

FIG. 3 shows a schematic side elevation view of a cage manufactured by the apparatus of the invention.

FIG. 4 shows a similar view of another cage manufactured by the apparatus of the invention.

[Explanation of symbols]

10 Jig 12 Housing 16, 24 Plug 20 type 28 Mandrel 32,52 Mandrel 34, 38, 54 thread 40 Annular space 42 Coating 46 Powder 48 Open space 50 Cage 58 Tsuba

Claims (19)

[Claims] 1. A method for manufacturing an electrolyte holder for an electrode for a chemical battery, comprising: forming a layer of particulate material containing a solid electrolyte or a precursor thereof around an externally threaded mandrel; Uniform pressure forming of a layer of particulate material to form a green cage with internal threads formed by the threads of the mandrel; axially threading the mandrel out of the green cage; sintering the green retainer to provide a retainer in the form of a single polycrystalline ceramic solid electrolyte workpiece. 2. The method of claim 1, wherein the layer of particulate material is a powder and the powder layer is compressed uniformly against a mandrel by a mandrel and a flexible coating that encapsulates the powder layer. . 3. The coating is encapsulated in a mold, the coating is elastically flexible and forms a lining for the mold prior to pressing, and the powder forms a layer of powder. The pressure forming is by means of a liquid introduced into the mold on the outside of the coating, and fluid pressure is applied to the mold. The mandrel and green cage are then removed after pressing so that the coating can spring elastically off the green cage to form the lining of the green cage, and the mandrel and green cage are then respectively removed from the cage. 3. The method of claim 2, wherein the mold is removed by unrolling. 4. The layer of particulate material is a powder, the powder layer encapsulating a mandrel, and a flexible coating disposed between the mandrel and the powder layer encapsulating the powder layer. 2. The method of claim 1, wherein the mold is uniformly squeezed outwardly away from the mandrel. 5. The coating is elastically flexible and forms a lining to the mandrel prior to pressing, the powder filling the space between the coating and the mold to form a layer of powder. the pressure forming is due to a liquid introduced into the coating between the coating and the mandrel;
Fluid pressure is then removed after pressing to allow the coating to spring back resiliently away from the green retainer to form a lining to the mandrel and the green retainer. each of which is unscrewed from the retainer and removed from the mold.
The method described in. 6. The particulate material is a powder, the mandrel and the powder layer are encapsulated by a flexible outer coating disposed in a mold, and a flexible inner coating is attached to the mandrel and the powder layer. disposed between powder layers, the powder layer being simultaneously squeezed inwardly by the outer sheath by a fluid introduced into the mold outside the sheath and within the inner sheath between the inner sheath and the mandrel. 2. The method of claim 1, wherein the inner coating is squeezed outwardly away from the mandrel by a fluid introduced into the inner coating. 7. Each coating is resiliently flexible, the inner and outer coatings lining respective mandrels and molds prior to compaction, and the powder is applied to each to form a powder layer. fluid pressure introduced into the space between the sheaths and between the inner sheath and the mold and the outer sheath, respectively, causing the inner and outer sheaths to rebound, respectively, to line the mandrel and the mold; 7. The method of claim 6, wherein the mandrel and green cage are each removed from the mold by being unscrewed from the cage. 8. Claim 3, wherein the mold is internally threaded and the removal of the retainer from the mold is by axially unscrewing the retainer from the mold. 5
and 7. The method according to any one of 7. 9. Apparatus for use in the method of claim 1, comprising a mandrel having an externally threaded surface and a flexible sheath, the mandrel containing particles to be uniformly squeezed by the sheath. Apparatus receivable within the sheath to provide an annular space around the mandrel for containing powder. 10. A mold, in which a mandrel is provided with a coating between the mandrel and the mold;
and wherein the mold and the mandrel are accommodating with a space defined within the mold between the mold and the mandrel, the mold and the mandrel forming respectively radial interior and exterior walls of the space. The device described in. 11. The device of claim 10, wherein the mold is internally threaded. 12. The coating is elastically flexible;
12. The device according to claim 10 or 11, and forming a lining on one of the walls of the space. 13. The device of claim 12, wherein there are two coverings, each forming a lining to the interior and exterior walls of the space. 14. Apparatus according to any one of claims 10 to 13, wherein the mold is a split mold. 15. Apparatus according to any one of claims 10 to 13, wherein the mold has an axially tapered interior. 16. Apparatus according to any one of claims 9 to 15, wherein the mandrel is axially tapered. 17. The method of claim 1 substantially as described herein. 18. The apparatus of claim 9 substantially as herein described and shown. 19. A solid electrolyte holder for holding electrodes of a chemical battery, produced by the method of claim 1.